1. Field of the Invention
The present invention is directed to the field of automatic swimming pool cleaners, and more particularly, to reverse flow valves for use with pressure cleaners.
2. Description of the Related Art
Automatic swimming pool cleaners for cleaning the floor and sidewalls of a swimming pool are well known. There are generally four types of pool cleaners in the pool cleaning market: pressure or return-side cleaners; suction cleaners; electric cleaners; and in-floor cleaners. Generally, “pressure” or return-side cleaners perform superior cleaning over the other three types of cleaners. Pressure-type cleaners use pressurized water from a pump into the cleaner to sweep and collect debris into a bag carried by the cleaner.
Pressure cleaners can be characterized into at least two categories—those requiring a booster pump and those which do not. Booster pumps are used in conjunction with the pool's skimmer pump to provide pressurized water to the cleaner at a rate sufficient to operate the cleaner effectively.
One particular type of known automatic pressure cleaner is shown and described in U.S. Pat. No. 5,933,899 (the “'899 patent”), fully incorporated herein by reference. The apparatus described in the '899 patent does not require a booster pump; rather, it is designed to operate using the lower fluid pressure of the pool's existing filtration pump. Another type of cleaner is shown in U.S. Pat. No. 6,003,184.
Both of these types of cleaner operates on pressurized water that is supplied to the cleaner through a supply hose. The water is used in part to drive the blades of a turbine which, in turn, rotates two or more of the wheels, and in part to induce a flow of pool water upwardly through the cleaner suction mast and into the collection bag. The drive wheels and a thrust jet propel the cleaner along the floor and sidewalls of the swimming pool. When the pool cleaner reaches an obstruction preventing further direct forward travel, the drive wheels impart a turning movement, causing the cleaner to turn and continue travel in a different direction. Alternatively, when the cleaner travels along the pool floor and reaches a smoothly curved region merging with a sidewall, the cleaner tends to travel through the curved region and crawl at least part way up the pool sidewall until the cleaner falls by gravity back to the floor of the pool. A ballast float mounted at the upper rear of the cleaner helps assure that the cleaner will land upright on the pool floor and resume travel in a forward direction.
In addition to the drive system, backup valves are coupled to the water supply line between the pumping system and the cleaner. Backup valves provide additional insurance that a cleaner will not get stuck in edges or corners of pools by forcing a reversal of direction of the cleaner at regular intervals.
Construction of backup valves is well known. In particular, one such valve includes a housing containing a fly wheel, rotating cover plate, and gearing. The housing has a water inlet, and at least two water outlets directed generally toward the opposite end of the housing from the inlet. One outlet is coupled by the supply line to the cleaner, while the other allows water to enter the pool directly, in a direction generally parallel to the supply line and the first outlet. Water is also prevented from entering the cleaner, thereby freeing backward movement of the cleaner. Water in the supply line enters the housing and drives the impeller to rotate the rotating cover plate to cover the first outlet and redirect water in the housing to the second outlet for a period of time determined by the gearing. The rotation of the gearing and the rotating cover plate determine the amount of time that water is allowed to flow to the cleaner, and the amount of time water flows into the pool to “backup” the cleaner.
With low pressure cleaners, that is, cleaners operating without the benefit of an additional booster pump, a difficulty has been found in obtaining the desired timing in backup valves due to the lower pressure of the water entering the inlet of the valve. Specifically, there is not enough pressure from the main water pressure source—without a booster pump—to accurately and regularly drive the impeller in the valve to ensure a constant spin rate and in some cases, not enough to even turn the wheel.
An improved backup valve is disclosed in U.S. Pat. No. 6,185,464 (the “'464 patent”). This valve is designed to be used in conjunction with a low pressure cleaner, requiring a lower volume per unit time of fluid to function effectively. Improvements to backup valves which can compensate for lower flow rates of pumping systems without booster pumps allow the backup valves to be used with a wider variety of pumps and cleaners.
Another issue in the performance of backup valves exists with the weight of the cleaner. The heavier the cleaner, the more force which must be provided by the valve to reverse the tension on the water supply line to reverse the direction of the cleaner.